In order to determine how much moisture is present it is best to perform a calcium chloride test to determine the moisture vapor emission rate (MVER) of a concrete slab. To perform the test, a small amount of calcium chloride (salt) is placed under plastic on a clean piece of concrete. The calcium chloride (salt) absorbs the moisture coming from the concrete slab over a period of about 72 hours. The weight gain of the calcium chloride is then measured and the moisture vapor emission rate MVER is calculated. If a high amount of moisture is present in the concrete (over 3 lb according to a calcium chloride test) it is best to use a moisture vapor barrier coating.
A calcium chloride test can be purchased directly through Amazon for about 18 USD.
Carpet manufacturers recommend the moisture vapor emission rate not exceed a 3 lb or 5 lb level before installing carpet.
The Vapor-Tek 440 is one of the best moisture vapor barrier coating products on the market to reduce moisture vapor transmission to levels that are acceptable for the installation of carpet. The high performance and quick installation features of this system make it an ideal solution to seal concrete from all water and moisture before installing carpet. The Vapor-Tek 440 will reduce moisture vapor emission rates of up to 20lb. / 24 hr / 1,000 ft. prior to the application of flooring.
Benefits include the protection of carpet, wood, vinyl and other flooring by reducing the effects of moisture vapor transmission. A properly sealed concrete floor will ensure the carpet remains dry and in optimal condition, at least from below.
Alternatively, if your concrete has never had a moisture or dampness problem and you are looking for a preventative, cost-effective solution, use the Lithi-Tek 4500 primer followed up seven days later by the Siloxa-Tek 8510 concrete sealer. The combination of the two products will reduce the porosity of the concrete making it less permeable to moisture. Althought it will not prevent a large amount of moisture from coming up through the concrete like the Vapor-Tek 440, it is an effective solution at making the concrete less porous.
